JP5814276B2 - Apparatus and method for radio frequency ablation (RFA) - Google Patents

Description

  The present invention relates generally to radio frequency ablation or RFA, the destruction of tissue in the form of coagulation necrosis caused primarily by resistive heating of the surrounding tissue and secondarily by passive heat conduction. In particular, the present invention relates to devices and methods that are predictable and adaptable to any size or shape of a tumor or diseased tissue, resulting in reliable coagulation.

  Surgical resection is still regarded as a top priority option for the treatment of malignant tumors. For unresectable tumors, several stromal techniques have been developed to achieve local tissue destruction, including radio frequency (RF) coagulation, cryosurgery, ethanol injection, interstitial laser therapy, and microwaves. Among these techniques, RF coagulation or RF ablation has had the greatest impact in recent experimental and clinical studies.

  Radio frequency ablation (RFA) is used as a minimally invasive heat-based method to cauterize tumors. RFA is mainly used for the treatment of liver cancer, but can also be used for cauterization of malignant tumors such as kidney, lung and bone. In RFA, a high frequency is emitted from a generator and passes through an uninsulated portion of one or more electrodes inserted into a target diseased tissue. Second, tissue destruction in the form of coagulation necrosis occurs as a result of secondary passive heat conduction, mainly as a result of resistive heating in the immediate surrounding tissue. Since resistance heating is inversely proportional to the square distance between the electrode and tissue, it occurs only within the tissue periphery that is in direct contact with the electrode. Beyond this periphery, the tissue is further heated as a result of passive conduction. However, RF radiation is easily censored as a result of increased impedance due to tissue desiccation and charring.

  Initial experiments with RFA on liver tissue were performed using a single simple metal electrode. The ablation diameter was rather limited to a maximum of 1.6 cm, due to the sudden rise in electrical impedance with current interruption. The limited ablation diameter was insufficient to allow tumor clotting through RFA. To be useful for tumor coagulation, the extent of tissue destruction should include the entire tumor and adjacent healthy tissue with a margin of 1 cm as a safe margin to prevent local recurrence.

  The first technical challenge in the development of RFA was to design an electrode that could increase the extent of coagulation lesions. Since 1994, a modified single-shaft electrode has been developed and tested. In general, the different trends in electrode development are to distinguish between internal cooling electrodes, electrode-tissue interfaces and expandable electrodes that expand the electric field, wet electrodes in which physiological saline is perfused into the tissue through the electrodes, and bipolar electrodes. Can do.

  Article "Radio frequency association using a new type of internally cooled electrode, etc. The author is active, and the switch is active in and out." Discloses a uniaxial internal cooling electrode that is adjustable through an insulating cover sheet connected thereto. An electrode having an adjustable active tip length is shown in FIG. 1 of the article by Cha et al. In vivo experiments have shown that different ablation volumes can be induced by adjusting the length of the exposed active tip.

  As described in the following paragraphs, there are several problems with uniaxial electrodes.

  First, the commercial version of the uniaxial electrode above produces a solidification that is smaller than expected, less predictable, less regular, and less complete. This leads to a high local recurrence rate of up to 60% due to incomplete clotting. The use of double clotting for larger tumors is unsafe because of the high recurrence rate as a result of the skipped sites remaining. Furthermore, tumors usually do not fit into the predefined oval, spherical, or discoid shapes that are commonly ablated with these uniaxial electrodes. As a result, tumor coagulation is incomplete, again leading to high recurrence rates, or a large amount of healthy tissue surrounding the tumor is coagulated.

  Secondly, apart from wet electrodes, these electrodes have a complex design and can only be used once and are therefore very expensive, currently between 1000 and 1500 euros.

  Third, none of these electrodes function to coagulate multiple tumors, each having its own shape and size. However, in clinical practice, a patient can have several tumors. As a result, it may be necessary to treat all tumors simultaneously or sequentially using two or more uniaxial electrodes on the same patient.

  In addition, some of these electrodes, such as bipolar wet electrodes, can generate very large lesions, but the size and shape of the coagulation zone is unpredictable. Such excessive clotting must be avoided to avoid damage to healthy organ tissue and inert structures near the tumor.

  In summary, the reliability and safety of single-axis electrodes of RFA are insufficient. RFA single-axis electrodes cannot be reproducibly adapted to tumors of any size and shape, are not sufficient for safe and healthy tissue and important structures around the tumor, are complex and expensive .

  The most promising evolution of RFA is the introduction of multi-electrode devices since 2001. Multi-electrode RFA devices implement a combination of the use of multiple electrodes. A distinction can be made between monopolar multi-electrode RFA devices or bipolar multi-electrode RFA devices. In a unipolar mode device, current flows from all electrodes toward the ground pad and has the same polarity. In a bipolar mode device, current flows between two electrodes or groups of electrodes of different polarities. Further, multi-electrode RF devices can be classified as operating sequential modes, simultaneous modes, or switching modes. When operating sequentially, the second electrode is activated after completion of the first electrode session, and so on. When operating simultaneously, all electrodes are activated during the same time interval. In the switching mode, the electrode subgroups are activated alternately using the switch box and the controller. The following paragraphs give an overview of known multi-electrode RFA devices operating in switching mode and their limitations.

  Author D. Haemmerich, D.M. J. et al. Schutt, J. et al. A. Will, R.A. M.M. Trigel, J. et al. G. Webster, and D.C. M.M. The article “A device for radiofrequency assisted hepatic rejection” from Mahvi describes an RFA device with six electrodes held in place by a Teflon guide. As shown in FIG. 3, the controller (PC) and electrode switch box activate adjacent electrode pairs in 0.5 seconds per pair in switched bipolar mode. As explained in the second paragraph of Section II C, the RFA process is performed through D.D. It is further monitored by an apparatus such as Haemmerich. As soon as the impedance between the electrode pair exceeds a certain threshold, the power supplied to this electrode pair is interrupted for 10 seconds.

  D. In the multi-electrode RFA device described in the article by Haemmerich et al., Large slices of equal length can be heated simultaneously through a fast switching mode, but still cannot adapt to various patterns. This limits its usefulness to clinical practice.

  The name is “Multipolar Radiofrequency Ablation: First Clinical Results”. Tacke, A .; Mahnken, A .; Roggan, and R.A. W. Another article by Guenther describes a device with three electrodes inserted and held in place using plastic triangles with standardized distance control. The electrode is a probe that is cooled by physiological saline that is sequentially activated in pairs in bipolar mode. With the switch box, 30 possible combinations are possible in which the electrode pairs are activated alternately for 2 seconds each. J. et al. The device such as Tacke further performs impedance control, the RF activation frequency is proportional to the tissue impedance, and if the tissue impedance increases beyond the limit, the coagulation process is terminated.

  D. Just like Haemmelich, J.M. Tacke et al. Discloses an apparatus that maximizes the achievable lesion size through bipolar activation of multiple electrodes in a switching mode. The shape of the solidification volume is rather pre-designed or pre-made. Any deviation from the pre-made shape requires multiple sequential insertions of the electrode into the same patient, or requires excessive secondary destruction of healthy tissue.

  Author D. Haemmerich, F.M. T. T. et al. Lee, D.C. J. et al. Schutt, L.M. A. Sampson, J .; G. Webster, J.A. P. Fine, and D.C. M.M. In another article from Mahvi called “Large-Volume Radiofrequency Ablative of ex Vivo Bobine Live with Multiple Cooled Cluster Electrodes”, the Plexiglas A plate with the cooled Plexiglas A A comparison of the sequential mode, simultaneous mode, and switching mode of the device is made. The electrode has a fixed exposed electrode length of 2.5 cm and operates in monopolar mode. This article shows that the most uniform heating is achieved when implementing the switching mode. The device also implements impedance feedback to cut off the power for 15 seconds whenever the impedance increases to a certain degree above the reference level.

  D. Haemerich et al. Have shown that switching mode is advantageous for achieving uniform heating and tissue coagulation, but the device is not adaptably controllable to any size and geometry of the tumor, and the prototype device Is certainly not adapted to coagulate multiple tumors of a patient in a reliable manner, thereby avoiding excessive destruction of healthy tissue and organic matter.

  WO 2004/082498, an international patent application named “Surface Electrode Multiple Mode Operation”, includes an RFA having a base (102) and a plurality of electrodes with adjustable penetration depth and active tip length. A system is disclosed. The penetration depth and active tip length of the electrode can be adjusted through the screwing of the electrode and a sliding electrically insulating sleeve extending from the base surface along the electrode. The electrodes can operate in a bipolar fashion or the electrode combinations can be selectively placed in a bipolar configuration relative to one another. However, such a bipolar configuration does not guarantee an accurate and predictable coagulation that can fit any size tumor.

  European Patent Application No. 1 645 239, a European patent application named “Cool-tip Combined Electrode Introducer”, includes a central reference electrode and a circularly positioned electrode with adjustable penetration depth and active tip length RFA will be described through a system having: Through dedicated monitoring equipment such as an ultrasonic scanner (15) and data processor (16), the insertion depth is monitored and the radio frequency ablation (RFA) process is also monitored in real time. However, EP 1 645 239 also describes how to activate the central electrode and the circularly positioned electrode to allow accurate and predictable coagulation that can be adapted to tumors of any size Does not teach.

  It is an object of the present invention to disclose a radio frequency ablation (RFA) apparatus and method that overcomes the disadvantages of the apparatus described above. In particular, it is an object to disclose an RFA apparatus and method that provides RF coagulation of diseased tissue that is predictable and compatible with tumors of any size or shape. Disclosed are RFA devices and methods that can treat large non-spherical tumors, treat tumors in the vicinity of structures that must not be destroyed, and treat multiple tumors of different sizes and shapes in one patient It is a further objective. It is a further object of the present invention to provide an RFA device that can be configured to be reproducible, non-complicated, inexpensive, and without mistakes, to treat one or more tumors of any size or shape. Is to present.

According to the present invention, the above mentioned object is realized by a device for radio frequency ablation (RFA) of diseased tissue according to claim 1, which device comprises:
A mesh or plate having holes in a grid to hold the electrodes;
A plurality of electrodes having compatible active tip lengths;
-Means for visualizing and investigating the insertion depth of each of the electrodes in the diseased tissue;
A switch box connectable to a plurality of electrodes and adapted to distribute current between the plurality of electrodes during a radio frequency ablation (RFA) process;
A control unit for controlling the switch box;
-Means for monitoring a radio frequency ablation (RFA) process;
The control unit
-Electrode group,
An electrical mode for activating each electrode group,
The polarity of the electrodes within each electrode group,
-Group activation mode,
-Time intervals and sequence of group activation,
-Power output and current intensity,
-Configured to determine the duration of a radio frequency ablation (RFA) process, whereby each electrode is activated for an amount of time such that approximately equal radio frequency power is applied to diseased tissue per unit volume. The

  Thus, the device according to the present invention has a plurality of electrodes, the active portions of the plurality of electrodes being individually adjustable, and the insertion depth of the plurality of electrodes is to match the RFA coverage to the size and shape of the tumor to be treated In addition, it can be individually controlled and investigated. In this way, optimal coverage of the tumor volume (eg, plus a 1 cm safety margin on each side) can be achieved, thereby efficiently removing the tumor, reducing the risk of recurrence, And the destruction of healthy tissue surrounding the tumor is possible. Through the switch box and a control unit, for example a PC executing an operating algorithm for controlling the switch box, the device according to the invention can be used even when the tumor is large and / or has an irregular shape. It is further designed to obtain a reliable ablation zone including tumor and safety margin. In the case of a mesh, such as a nylon or silicone-like mesh, rather than a plate that holds the electrode, it is even possible to position the electrode flexibly so that it can adapt to the shape of the tumor and / or blood vessels, etc. The ability to avoid delicate structures is further increased. The flexibility allows the position of the electrode to be controlled after the electrode is inserted, for example by bending the mesh through ultrasound. The flexibility allows the mesh to be further wrinkled to conform to the shape of the tumor.

  The treatment algorithm executed by the PC or control unit that controls the switch box is designed so that the RFA process is optimally performed in order to obtain a reliable ablation zone tailored to the size and shape of the tumor. The input parameters of this algorithm may include the length of the active portion of the electrode, the number of electrodes, the distribution pattern and spacing of the electrodes in space, the tissue type, the presence or absence of tissue perfusion, the measurement impedance, and the like. Based on these inputs or a subset of inputs, the treatment algorithm determines which electrodes are activated as a group, in the electrical modes used to activate each military-monopolar, bipolar, multipolar, bipolar modes. Which electrode is activated as a positive electrode, which electrode is activated as a negative electrode, the activation mode of a specific group-sequential, simultaneous or switched, the activation time interval and group of each group activated The order of power generated, the power output and current intensity generated by the generator and supplied to the electrodes, the duration of the entire RFA process, etc. The algorithm determines these parameters adaptively during treatment, taking into account impedance feedback or other parameters that are monitored before treatment or, for example, during the RFA process. As a result of the algorithm, each electrode is activated for an equal amount of time and approximately equal radio frequency power is applied to diseased tissue per unit area to achieve efficient and reliable coagulation of the tumor and surrounding safety margin.

Optionally, as claimed in claim 2, the holes in the mesh or grid in the plate have the following shape:
A rectangular pattern,
-It may have one or more of spherical patterns.

  Thus, there may be one or more patterns on the mesh or plate: rectangular 3-5 × 3-5 holes, different electrode spacings, eg 1.5 cm, 2 cm, 3 cm, 4 cm, 5 cm Have Spherical grids with different electrode spacings as well as other possible configurations can be envisaged. The electrodes may be organized into a population, for example, a triangular, square, row, or hexagonal population. Different patterns and population shapes further increase the flexibility of adapting the ablation zone to the shape and size of the diseased tissue.

  Optionally, as claimed in claim 3, the mesh or plate in the device according to the invention may be provided with a plug for each hole to connect to the electrode inserted in the hole, the plug being around the hole. Positioned.

  Alternatively, as claimed in claim 4, the mesh or plate in the device according to the invention can be provided with a plug for each hole to connect to the electrode inserted in the hole, the plug being positioned in the vicinity of the hole .

  Thus, there may be a plug for each hole or opening in the mesh or plate to control the insertion depth of the electrode. The plug may be around or adjacent to the opening and is conductively connected to the electrode via electrical wires that interconnect the plug and, for example, the top of the electrode. The deformation where the plug is around the opening is more sophisticated and prevents the wire from moving around. When opening the package, the wire is wound on top of the electrode and slid down to connect to the plug. The disadvantage of this variant is that safety can be reduced with respect to the electrical insulation of the electrical contacts from the patient, especially in an environment wet with blood, saline or the like. The deformation where the plug is next to the opening is less sophisticated and allows the wire to move around. Plugs and openings typically occupy more space on the mesh or plate, which can be a problem when the electrodes are close to each other. However, this variant is safer with respect to electrical insulation.

Furthermore, optionally, as claimed in claim 5, the mesh or plate according to the invention comprises
An electrical cable connector for connection to the switch box;
-The electrical wiring between each plug and the electrical cable connector;
Can be provided.

  In fact, for each plug corresponding to a hole, there can be an electrical wire that is woven into the mesh or integrated into the plate. These individually insulated wires can be combined into one electrical cable connector that keeps the mesh or plate connected to the switch box. The electrical cable connector ensures that the electrode set can be connected to the switch box.

According to an advantageous optional aspect of claim 6, the mesh or plate or intermediate sterilization plate in the device according to the invention comprises
A visual indicator may be provided for each hole, the visual indicator being adapted to illuminate when the electrode is inserted into the hole, the visual indicator on the switch box indicating a plug on the switch box to which the electrode is to be connected Further operatively coupled to the visual indicator, the visual indicator on the mesh or plate and the visual indicator on the switch box allow for an error-free connection of the electrodes to the switch box.

  Thus, as an alternative to wiring and electrical cable connections integrated in the mesh or plate, the visual indicator on the mesh / plate and / or the visual indicator on the switch box can be used to detect errors in the electrodes to the switch box by the operator of the device. Can help with no connection. As soon as the electrode is inserted into the hole, the corresponding visual indicator on the mesh / plate and the corresponding visual indicator on the switch box are illuminated so that the operator plugs the wire attached to the electrode into the correct plug on the switch box. To be able to connect to. Apart from being correct, this embodiment of the present invention is advantageous in that it does not require the electrodes to be connected to plugs integrated in a mesh or plate, thus ensuring patient electrical isolation. . In a more user-friendly variant, the visual indicator (eg LED) is placed on an intermediate sterilization plate into which the electrode wiring can be inserted. Such an intermediate sterilization plate may be placed on the operating table, in a dry place of the patient, or may be held by a sterilizing robot arm that is fixedly mounted on the operating table and accessible to the physician for user friendliness. . The intermediate sterilization plate is connected to the non-sterile switch box via an electrical cable connector and an electrical cable. The intermediate sterilization plate, in other words, functions as an extension of the switch box user interface that allows the physician to control the switch box in a user-friendly manner from within the vicinity of the operating table, while the non-sterile switch box is a surgical Can be placed away from the table.

  In a first variant embodiment, only the mesh or only the plate comprises a visual indicator, for example an LED. This embodiment is useful when the computer identifies the location where the next electrode needs to be inserted, for example, fully automatically based on visual inspection and image processing. The computer controls and turns on the corresponding LED on the mesh or plate to assist the physician in the correct insertion of the t4he electrode.

  In another variant embodiment, only the switch box or only the intermediate sterilization plate implementing the switch box user interface comprises a visual indicator, for example an LED. The physician can, for example, identify the location where the next electrode needs to be inserted through ultrasound. When an electrode is inserted, the corresponding LED on the switch box or intermediate plate lights up, allowing the physician to connect the wiring without fail.

  As further specified in claim 7, the visual indicator on the mesh, plate or intermediate sterilization plate may consist of a color LED.

  In practice, when using different color LEDs on the mesh, plate, or intermediate sterilization plate, and using the corresponding color LED on the switch box, the device according to the present invention provides an alternative to electrode misconnection. Since this level of protection is easily constructed in this way, there is a further improvement with respect to the foolproof configuration.

  Further optionally, as claimed in claim 8, the mesh or plate constitutes a plate and the apparatus further comprises a robotic arm for positioning the plate.

  The plate has a certain thickness, e.g. 3-4 cm, to ensure parallel insertion of the electrodes. The plate may be placed directly on the organ that needs to be treated, such as the liver, or more preferably held by a robotic arm. The robot arm can be secured to the operating table. The robotic arm allows the plate to be held in a desired position and orientation, e.g. 5 cm above the organ to be treated, so that all electrodes can be inserted in parallel, e.g. into the diseased tissue Sufficient spacing is left in the ultrasound probe used to control the insertion depth and position of the electrodes. The electrode is inserted manually.

  Further optionally, as set forth in claim 9, the device according to the invention may comprise a robot arm for positioning a plurality of electrodes substantially parallel to each other.

  In fact, a robotic arm whose end consists of a plate preloaded with, for example, 5 × 5 electrodes can be positioned manually or by navigation to an organ to be treated, for example the liver. When the end of the robot arm is placed on the surface of an organ to be treated, for example, the liver, each electrode is sent out to a predetermined insertion depth by a mechanism that forms part of the robot arm itself. In the case of an electrode having an adaptive insulating sheet, which will be described later, the length of each electrode sheet can also be obtained mechanically, that is, not by hand, but by a mechanism within the robot arm itself. The number and position of the electrodes, the length of insertion, and the length of the sheet can be determined based on pre- and intra-operative imaging, either by individual electronic commands from the physician or completely automatically. The electrodes can be wired to the switch box in one of the ways described above.

  According to another optional aspect of the invention as set forth in claim 10, each electrode of the plurality of electrodes has a sliding electrical insulation sheet adapted to the active tip length.

  Thus, the length of the active part of the electrode may be individually adaptable, for example, by sliding an insulating sheet made of plastic over the electrode until the sheet is within 1 cm of reaching the leading edge of the tumor. . If this is done after the electrode has been inserted beyond the lower edge of the tumor to a depth of 1 cm, the length of the active part of the electrode is the thickness of the tumor tissue at the position where the electrode is inserted, on each side of the tumor. And 1 cm plus a safety margin. When following this procedure with each electrode, it is clear that the length of the active portion varies between electrodes inserted into the same tumor, depending on the local thickness of the tumor. Thus, optimal coverage of the entire tumor volume is achieved with perfect adaptation to any size and shape of the tumor.

  Further optionally, as claimed in claim 11, the electrically insulating sheet may be coated with a coating that is better visualized through ultrasound.

  Such a coated sheet makes it possible to monitor the sliding of the insulating sheet on the electrode through ultrasound. In this way, sliding the sheet to the correct position, i.e., within 1 cm of reaching the leading edge of the tumor, is an alternative solution where the slide is performed, for example, based on a grade mark on the electrode Even so, it is less susceptible to human errors that can still occur.

  According to another advantageous optional aspect of the RFA device according to the invention as claimed in claim 12, one or more of the plurality of electrodes are partially shielded along the outer periphery, thereby The generated RF field is directed near the boundary of the diseased tissue.

  In fact, when using simple electrodes in bipolar or multipolar mode, the tissue edges 0 cm to 1 cm solidify outside the volume created by interconnecting the outer electrodes. In order to avoid such undesired solidification outside the volume created by the outer electrodes, these outer electrodes can be partially shielded with an insulating sheet, for example over the outer circumference of 180 ° C. The insulating sheet can be made of plastic, for example. As a result, the edge of undesired solidification is absent or much narrower.

  Further optionally, as claimed in claim 13, each partially shielded electrode has a shape that prevents its rotation when the partially shielded electrode is inserted into the diseased tissue. Can do.

  Thus, these electrodes can be given a directional shape that prevents such rotation so that the outer electrodes, partially shielded along the outer perimeter, do not rotate once inserted into the tissue. . The directional shape may be a blade or may consist of a small airfoil extension that prevents rotation of the circular electrode when inserted into tissue. If the partially shielded outer electrode rotates, the effect of reducing unwanted coagulation outside the volume produced by the outer electrode may disappear, or at least not optimal.

  As claimed in claim 14, the plurality of electrodes may optionally have different lengths.

  Therefore, as an alternative to an electrode with a sliding insulating sheet, the length of the active part of the electrode can be adapted to the local thickness of the tumor by selecting an electrode with the correct active length prior to electrode insertion. Can do. In this way, the ablation zone can be adapted to the size and shape of the tumor so that the entire tumor volume plus the safety margin is completely covered.

Further optionally, as defined in claim 15, the means for monitoring with the RFA device according to the present invention comprises:
-A ground plate;
-Means for measuring the impedance between the ground plate and each electrode of the plurality of electrodes;
Can be provided.

  The ground plate may be placed on a part of the patient's body, at a specific distance from the electrodes, usually in the thigh in the case of liver treatment. The ground plate functions to measure the electrical impedance between each individual electrode and the ground plate at regular time intervals before or during the RFA process. As described below, impedance measurements can assist in calculating the insertion depth or active portion length of each electrode, allowing it to check which position within the gridd hole is occupied by the electrode, Allow the coagulation process to be monitored to interrupt, stop, or control the ablation process.

Alternatively, as defined in claim 16, the means for monitoring in the RFA device according to the present invention comprises:
-Means for measuring the impedance between each pair of electrodes;

  Thus, in an alternative embodiment, ground plates can be avoided and impedance measurements can be made between electrode pairs. Impedance can be measured at a standard frequency of 500 kHz or below or above.

According to another alternative as claimed in claim 17, the means for monitoring in the RFA device according to the invention comprises:
-Means may be provided for measuring the impedance between the reference electrode and each non-reference electrode of the plurality of electrodes;

  In this variant embodiment, a ground plate is also avoided and a reference electrode is introduced to assist impedance measurement. Again, the impedance can be measured at a standard frequency of 500 kHz, or below or above. Impedance can be measured during insertion of the electrode into the tissue. Since diseased tissue and healthy tissue have different impedances, the curve representing the variation in impedance during electrode insertion is a significant change at the point where the electrode tip enters the diseased tissue, and the electrode tip exits the diseased tissue. And a second important change in points. The physician may use these points to determine the insertion depth of the electrodes, or these points may function to light an LED or other visual indicator that is shown to the physician. The reference electrode itself can have two zones: a first zone near the tip and a second zone along the axis, and the impedance between these zones is measured upon insertion. Next, the change in impedance variation shows when the tip of the reference electrode enters the tumor and when it exits the tumor.

Further optionally, as claimed in claim 18, the device according to the invention comprises:
Means for converting the impedance into information indicative of the position within the occupied mesh or plate;
Means for converting impedance into information indicating the active tip length of each electrode;
One means of converting impedance into information indicative of the progress of a radio frequency ablation (RFA) process; and one of means for converting impedance into information indicative of confirmation of coagulation after the radio frequency ablation (RFA) process. Or a plurality may be further provided.

  By measuring the pre-treatment impedance between electrode pairs, between the electrode and the ground plate, or between the electrode and the reference electrode, which position within the gridd hole is occupied by the electrode, and which position is occupied You can check if it is not. In the latter case, the measured impedance is theoretically infinitely large. The active tip length of the electrode can also be calculated by measuring the impedance before treatment. If the characteristic impedance before treatment of healthy tissue is approximately equal and the characteristic impedance of diseased tissue before treatment is approximately equal, but is assumed to be higher than that of healthy tissue, the change in measured impedance during electrode insertion is This is due only to the length of the electrode part exposed to. The impedance begins to increase as the electrode tip enters the vicinity of the leading edge of the tumor and begins to decrease as soon as the electrode tip leaves the lower edge of the tumor. Similarly, by measuring impedance intermittently during the ablation process, the impedance rises as a result of tissue coagulation, so the progress of the ablation process can be monitored in 2D or 3D. A sufficiently high impedance may indicate that the target tissue can be deactivated and the ablation can be temporarily interrupted locally or entirely or the ablation can be stopped in a timely manner. Finally, post-treatment impedance measurements can indicate the presence / absence of disease / healthy tissue or can confirm the degree of coagulation. If diseased tissue is present, the tumor has not yet been completely cauterized and RFA treatment must be repeated or continued.

  Further optionally, as claimed in claim 19, the control unit is adapted to activate the electrode group during successive cycles in which the centrifuge mode and the centripetal mode alternate.

  In fact, in the case of rows with equal polarity, ie one row with positive-positive-positive -... electrodes and one row with negative-negative-negative -... electrodes, between the electrode groups The central part is less solidified by the Faraday effect. In the case of rows with alternating polarities, ie one row with positive-negative-positive -... electrodes and one row with negative-positive-negative -... electrodes, the central part between the electrodes Will coagulate excessively due to centripetal current. Thus, in a preferred embodiment, the algorithm for controlling the switch box controls a group of electrodes during successive cycles to have centrifuge schemes with electrodes of the same polarity in the rows and electrodes of alternating polarity Alternating with centripetal method.

Optionally, as claimed in claim 20, the device according to the invention comprises
Means may further be included for logging parameters prior to and during a radio frequency ablation (RFA) process.

  In fact, for example, the PC can log different parameters before and throughout the treatment: electrode current, power, impedance, position, length, etc. These parameters can be stored and visualized graphically, printed, or kept in a patient's medical record or the like.

As claimed in claim 21, the device according to the invention optionally comprises:
It may further include means for visualizing the progress of the radio frequency ablation (RFA) process via a two-dimensional (2D) representation and color in response to impedance measurements.

  Indeed, the 2D representation on the screen can visualize, for example, the positions of the electrodes represented by dots as well as the area covered by each electrode represented by, for example, a square or circle. The square or circle color may represent the impedance measured locally. The color scale can vary from 0Ω to a fixed value of, for example, three times the pre-treatment impedance or 300Ω to maximize the visibility of impedance changes during the ablation process. The square or circle of the position of the unoccupied electrode may be shown for each square or circle, or may not be shown, or may be shown when the square or circle is clicked or touched with the mouse.

Alternatively, as defined in claim 22, the device according to the invention comprises
Considering the active tip length of the electrode and the color responsive to impedance measurement, it may further comprise means for visualizing the progress of a radio frequency ablation (RFA) process via a three-dimensional (3D) representation.

  In fact, a third dimension can be added on the screen based on the length of the active portion of each electrode. The square or circle is then replaced with a bar or elliptical volume whose length corresponds to the length of the active portion. The virtual image thus obtained can be fused with a 3D representation of the tumor so that the position of the electrodes and the progress of the ablation process can be visually monitored on the screen.

  Further optionally, as claimed in claim 23, the device according to the invention may comprise an RF control interface of the switch box and / or the power unit.

  Such an RF controller allows distributed control of the switch box and / or generator. The RF controller functions as an extension to the switch box or generator user interface and can be integrated into a sterilization plate or housing, for example, for use by physicians at or near the operating table. A single RF controller connected to the bus and controlled from the master controller may be provided for each switch.

In addition to the RFA device of claim 1, the present invention is also applied to a corresponding method of treating diseased tissue through radio frequency ablation (RFA) of claim 24, the method comprising:
Providing a mesh or plate with gridd holes to hold the electrodes;
-Inserting a plurality of electrodes having adaptable active tip lengths into the holes;
-Visualizing and investigating the insertion depth of each of the electrodes in the diseased tissue;
-Connecting a plurality of electrodes to the switch box;
-Controlling the switch box to distribute current between the plurality of electrodes during a radio frequency ablation (RFA) process;
-Monitoring a radio frequency ablation (RFA) process;
Including
The steps to control the switch box are:
-Electrode group,
An electrical mode for activating each electrode group,
The polarity of the electrodes within each electrode group,
-Group activation mode,
-Time intervals and sequence of group activation,
-Power output and current intensity,
-Determining the duration of the radio frequency ablation (RFA) process, whereby each electrode is activated for an amount of time such that approximately equal radio frequency power is applied to diseased tissue per unit volume .

  As further indicated in claim 25, the diseased tissue undergoing the method according to the invention may comprise a brain tumor, in which case the electrode is a rigid needle.

  In fact, especially in the case of brain tumors where the margin of coagulation is very small and edema outside the coagulation zone can cause excessive pressure and edema leading to increased intracranial pressure, it is tailored to the size and shape of the (smaller) brain tumor. Very accurate and predictable control of the ablation zone is extremely important and can be achieved through the switch box control algorithm according to the invention. Embodiments of the present invention that remain rigid to avoid deformation when the electrodes are miniaturized and inserted into soft brain tissue, ie, embodiments in which a matrix of needle electrodes is used, provide radiofrequency ablation for brain tumors. The prejudices of the medical society that cannot be applied to the medical

Preferably, as claimed in claim 26, the method according to the invention applied to a brain tumor comprises:
-Performing preoperative imaging;
-Determining the orientation of the needle electrode, the insertion depth, and the active tip length according to the optimal insertion path determined during preoperative imaging;
Creating a pre-formed cluster of needle electrodes taking into account orientation, insertion depth, and active tip length;
-Robotically inserting a pre-made needle electrode cluster into a brain tumor;
including.

  Thus, when applied to brain tumors, the method according to the present invention preferably utilizes pre-made needle electrode clusters, which are simultaneously inserted into the brain by a robot. Such pre-made needle clusters are less preferred when treating diseased tissue in large organs such as the liver, long, or kidneys due to the moving membranes of these organs, while Pre-made needle electrode clusters are advantageous for the treatment of brain tumors to avoid uncontrolled relative movement of needle electrodes inserted into soft brain tissue.

Alternatively, as indicated in claim 27, the method according to the invention applied to a brain tumor comprises:
-Performing preoperative imaging;
-Determining the orientation of the needle electrode, the insertion depth, and the active tip length according to the optimal insertion path determined during preoperative imaging;
Sequentially robotically inserting needle electrodes into the brain tumor, taking into account orientation, insertion depth, and active tip length;
including.

  In fact, instead of pre-creating needle electrode clusters using a predetermined fixed relative distance, orientation, insertion depth, and active tip length, for example, needle electrodes are prepared and inserted sequentially, ie, one after another by a robot May be.

  When inserted one by one, the method according to the invention applied to brain tumors preferably comprises using an intermediate plate that maintains the needle electrode in place during sequential insertion. This is described in claim 28.

  A method according to the present invention for applying needle electrodes simultaneously or sequentially using a robot applied to a brain tumor as claimed in claim 29, preferably with reference to the brain coordinate system in the robot coordinate system and the needle Locating the brain tumor during insertion.

  Therefore, the localization mechanism needs to associate the 3D brain coordinate system or the tumor coordinate system with the 3D robot coordinate system. This is based on target criteria attached to the patient's skull and visualized through MRI, based on three LEDs and pellets visualized through MRI, using conventional localization mechanisms and through normal cameras It can be realized by fitting or matching the visualized skill patterns.

As specified in claim 30, the method according to the invention applied to a brain tumor comprises:
-Temperature monitoring and feedback step;
-Controlling the radio frequency ablation (RFA) process, thereby maintaining the temperature below 60 ° C;
May further be included.

  Such slow ablation based on temperature monitoring and feedback can reduce heat diffusion in the brain and avoid charring around the electrodes. The temperature sensor may be inserted separately or, alternatively, in combination with / integrated with the needle electrode.

  According to a further optional aspect as claimed in claim 31, the method according to the invention may comprise the step of fringing the radiofrequency ablation zone using one or more cooling electrodes.

  Protects these structures from ablation through the use of one or more cooling electrodes that form a cage that delimits the ablation zone, especially when applied to the treatment of brain tumors near critical nerves, blood vessels, or other brain structures Can do. For example, using a needle electrode that is partially shielded along the border of the ablation zone or at the corner of the ablation zone further improves the control of the ablation zone and in the treatment of brain tumors to delimit the ablation zone. Can be advantageous.

  As indicated in claim 32, the method according to the invention may use electrodes of different thicknesses. One example is an embodiment having a central thick electrode surrounded by a thin needle electrode.

FIG. 1A shows a mesh or plate having a rectangular pattern of holes for holding electrodes in an embodiment of an RFA device according to the present invention. FIG. 1B shows a mesh or plate having a spherical pattern of holes for holding electrodes in an embodiment of an RFA device according to the present invention. FIG. 2A shows a hole with a hole around it in an embodiment of an RFA device according to the present invention. FIG. 2B shows the insertion of the electrode into the hole shown in FIG. 2A. FIG. 2C shows a hole with a plug in the vicinity of an alternative embodiment of an RFA device according to the present invention. FIG. 2D shows the insertion of the electrode into the hole depicted in FIG. 2D. FIG. 3 shows a mesh or plate with integral wiring and electrical cable connections in an embodiment of an RFA device according to the present invention. FIG. 4A shows an embodiment of an RFA apparatus according to the present invention having a plate and a robot arm. FIG. 4B shows an embodiment of an RFA apparatus according to the present invention having an electric robot arm. FIG. 5 shows an electrode with an active part length that can be accommodated appropriately in an embodiment of the RFA device according to the invention. FIG. 6 shows an electrode having a grind sheet used in the embodiment of the RFA apparatus shown in FIG. FIG. 7 shows a 3 × 3 electrode activation scheme with a group of 2 × 2 electrodes. FIG. 8 illustrates a 4 × 3 electrode activation scheme with a group of 3 × 2 electrodes. FIG. 9 shows a 3 × 3 electrode activation scheme with a group of 3 × 2 electrodes. FIG. 10 shows the centrifugal polarity in the activation mode of FIG. FIG. 11 shows the centrifugation polarity in the activation mode of FIG. FIG. 12 illustrates a 4 × 4 electrode activation scheme having a group of 4 × 2 electrodes. FIG. 13 shows the positioning of the electrodes when a spherical or cylindrical volume is to be solidified. FIG. 14 shows an alternate positioning and activation scheme when a cylindrical volume is to be solidified. FIG. 15 shows an embodiment of a switch box in an RFA device according to the present invention. FIG. 16 shows the connection of a single switch to the communication bus in the embodiment of the switch box shown in FIG. FIG. 17 illustrates a two-dimensional (2D) visualization of the RFA process to the screen in an embodiment of the present invention. FIG. 18 shows a three-dimensional (3D) visualization to the screen of the RFA process in an alternative embodiment of the present invention. FIG. 19 illustrates solidification outside the zone surrounded by electrodes in an embodiment of the present invention. FIG. 20 shows a partially shielded electrode used in an advantageous embodiment of the RFA device according to the invention. FIG. 21 illustrates solidification outside the zone surrounded by electrodes in an embodiment of the present invention where the partially shielded electrode of FIG. 20 is used.

A preferred embodiment of adaptive radio frequency ablation (RFA) according to the present invention is:
-A mesh or plate with patterned electrode guides, electrical connectors and integrated electrical circuits;
-A plurality of adjustable electrodes,
An adjustable guide device,
-Ground plate,
-Switch box,
A personal computer (PC),
-Operation algorithm,
-Log of actions,
-Visualization of electrode position, electrode impedance, active length, and activation state (positive or negative);
-PC with data, menu introduction,
-It consists of an integrated combination of generators capable of working up to 500W and working with low impedance.

  1A and 1B show an embodiment of a mesh or plate having patterned electrode guides, electrical connectors, and integrated electrical circuits. A plurality of electrodes can be arranged in a fixed cluster, for example, a triangular, square, row, or hexagonal cluster by means of a mesh or plate. Alternatively, the electrode can be inserted through a block having parallel perforations. While such blocks are useful for in vitro experiments, they are not useful in treating patients because the blocks are heavy and disturbing. The block (and also the plate) cannot be flexibly positioned to fit the shape of the tumor, or to avoid delicate structures such as blood vessels. Manual positioning of the electrodes is very flexible but does not guarantee parallel insertion in a very regular equidistant pattern. Furthermore, because there is one electrical cable for each electrode, many cables are easily confused. Cables at the ends of different electrodes also have a tendency to bend these electrodes. Great care must be taken to properly connect the cables one by one to the rigid connector of the generator (or the switch box between the electrode and the generator). This is a time consuming task that must be done carefully by the operator or physician. One mistake can ruin the outcome of the treatment.

  In a preferred embodiment of the present invention, the problem is that the composite is made of, for example, nylon, which is not resilient like plastic and matches a highly flexible fabric that is not elastic like cotton. This is solved by using a mesh. Alternatively, the mesh can be a silicone-like transparent or opaque flexible mesh.

  In the mesh or plate, a grid of holes for inserting the electrodes is foreseen. Advantageously, for example, different electrode spacing, e.g. 3-5 holes with 1.5 cm, 2 cm, 3 cm, 4 cm, 5 cm x rectangular grid with 3-5 holes, with different electrode spacing There are several patterns such as a spherical grid, and other possible configurations. FIG. 1A shows a mesh 100 with holes 101 in a rectangular grid, while FIG. 1B shows a mesh 110 with holes 111 in a spherical grid.

  Flexibility allows the mesh or plate to bend after electrode insertion so that position can be controlled and monitored through ultrasound. Flexibility can also wrinkle the mesh or plate to conform to the shape of the tumor or avoid delicate structures such as blood vessels.

  At each mesh or plate opening, a plug is attached or integrated into the mesh or plate. The plug can be placed around the opening, as shown in FIGS. 2A and 2B, or the plug can be placed directly next to the corresponding hole, as shown in FIGS. 2C and 2D. Also good.

  Embodiments having plugs 202 + 203 or 212 + 213 around the opening are more sophisticated because they consume less space and have less movement around the wire 216. Note that the plug consists of a plastic part 203 or 213 and a conductive metal part 202 or 212. Plug 215 and wire 216 can be wound on top of electrode 201 or 211 when opening the package. The plug 215 is then slid down to connect to the conductive portion 202 or 212 of the plug integrated on the mesh or plate 209 or 219. 2A and 2B further illustrate the wiring 204 or 214 integrated in a mesh or plate. The wiring can be integrated into the mesh or placed on the intermediate sterilization plate or the front panel of the switch box and used to control the LED indicator that will definitely assist the physician in connecting the electrodes.

  Embodiments having plugs 222 + 223 or 232 + 233 in the vicinity of opening 227 or 237 are somewhat less sophisticated because wire 236 is more easily movable around and the space occupied by the opening and plug is larger. The larger space occupied can be a problem especially when the electrodes are close to each other. Again, note that the plug consists of a plastic portion 223 or 233 and a conductive metal portion 222 or 232. A wire 236 extending from the top of the electrode 221 or 231 terminates in a plug 235 that connects to a conductive portion 222 or 232 of the plug integrated in a mesh or plate. Versions with plugs in the vicinity of the corresponding holes are safer with respect to electrical insulation, and precise measurement of depth taking into account the height of the mesh or plate is not a problem. 2C and 2D further show the wiring 224 or 234 integrated on the mesh or plate 229 or 239. FIG.

  As shown in FIG. 3, the electrical wires 302 and 303 are woven into a mesh for each hole and corresponding plug 301 or integrated into the plate 300. These individually insulated wires are combined into a single electrical cable connector 304 that exits the mesh or plate 300 and is connected to the switch box.

  As an alternative to a flexible mesh or plate, the electrode 405 can be carried through a multi-perforated plate 404 with holes every 1 cm, for example, as shown in FIG. 4A. The plate 404 may be solid, perforated, or hollow, and a small tube connects the upper and lower surfaces of the plate. Alternatively, if the plates and tubules are sufficiently rigid to ensure parallel insertion, the upper or lower surface plate can be omitted. All holes have electrical plugs and electrical wiring, but not all holes need to be used for RFA procedures. This plate 404 has a certain thickness, for example 3 cm to 4 cm, to ensure parallel insertion of the electrodes. The plate can be placed directly on the organ of the patient 402 in need of treatment, such as the liver. More preferably, the plate 404 is held by a robot arm 403 fixedly attached to the operating table 401. Such a robot arm 403 allows the plate 404 to be held in a desired position and orientation, usually 5 cm above the organ to be treated, so that all electrodes 405 can be inserted in parallel, Leave enough space for the ultrasound probe to control the insertion depth and position of the electrode 405. The robot arm 403 is manually moved to a desired position. Alternatively, the robot arm 403 includes position measuring means.

  FIG. 4B shows an alternative embodiment having a fully automated robot arm 412, where the end of the robot arm 412 consists of a plate 411 preloaded with electrodes 413. The robot arm 412 is positioned by navigation to the organ to be treated, for example, the liver. The robot arm 412 includes a position measurement system and a motor that automatically moves the arm 412 and the electrode 413. The electrode 413 is fed out by an electric mechanism that forms part of the robot arm 412 itself. The insertion depth is based on preoperative and intraoperative imaging of the tumor and tumor bearing organ. The electrodes are wired in the same manner as described above.

  The length of the active part of the electrode preferably corresponds to the thickness of the tumor tissue 500 at the electrode location plus a 1 cm safety margin on both sides. This is shown in FIG. 5 for a number of electrodes 501, 502, 503, 504, 505, 506, 507, 508, 509, 510 used in the treatment of the liver tumor 500 of the patient 511 in the RFA process. The active tip length 601 of the electrode can be accommodated by sliding an insulating plastic sheet 602 over the electrode until it is within 1 cm of reaching the leading edge of the tumor. This is shown in FIG. 5 with the upper part of the electrode left white. Before the sheet 602 slides, the electrode 600 must be inserted to the preferred depth, i.e. 1 cm below the lower edge of the tumor. Insertion of the electrode 600 to the preferred depth and sliding to the preferred depth of the sheet can be performed using ultrasound or deformation techniques that visualize the electrode. FIG. 6 further shows a handle 603 on the electrode, wiring 604, and indicia 605 that can assist in sliding the insulating sheet 602 to the appropriate depth.

  Alternatively, in the simple case of having a limited number of electrodes, the lengths of these electrodes may be different, and the physician can select an electrode with the correct active length at each location prior to electrode insertion.

  The length of the active part can vary according to the local thickness between electrodes inserted into the same tumor. As a result, an optimal covering of the entire tumor volume 500, preferably adaptable to each size and shape, can be achieved.

  When inserting electrodes through a pre-wired mesh or plate, a passive robot arm can be used to ensure that the electrodes are completely parallel to each other. With an adjustable guide device, electrodes can be inserted with minimal guidance from ultrasound guidance, regardless of patient pace constraints.

A ground plate is typically placed on the thigh at a specific distance from the electrodes on the patient's body part. The ground plate is used to measure the electrical impedance between each individual electrode and the ground plate at regular time intervals before or during the cauterization process, or both. Such an impedance measurement gives triple types of information.
If the pre-treatment characteristic impedance of the tissue is equal at all electrode positions and the distance from each electrode to the ground plate is approximately equal, the measured impedance difference is due to the difference in the length of the exposed electrode tip Is. The impedance decreases linearly with increasing exposed tip length. Therefore, the PC can easily calculate the length of each electrode.
-Measurement of the pre-treatment impedance can check which position in the grid is occupied by the electrode and which position is not occupied. In the latter case, the impedance is infinitely high.
-By intermittently measuring impedance during the ablation process, further 2D or 3D monitoring of the RF process is possible, stopping the ablation if a sufficiently high impedance indicates that all target tissues have been deactivated be able to.

  The switch box forming part of the device according to the invention may be alone or integrated into the generator. The switch box receives coupled electrical wiring from the mesh or plate. The switch box allows spatial control of multiple electrodes. The switch box includes hardware that can redistribute current across different electrodes and between different electrodes. The switch box also includes a variable electrical resistance that can be incorporated into the circuit to instantaneously change the current that actually flows between a particular electrode pair at a particular moment.

As already indicated above, the RFA device according to the invention is preferably
-Operation algorithm,
-Log of actions,
-Visualization of electrode position, electrode impedance, active length, and activation state (positive or negative);
-Includes PC with data, menu introduction.

  The PC allows the ablation process to be steered by controlling or commanding the switch box. In a possible implementation of the RFA device, the basic current is set on the front panel of the generator. In an alternative version of the RFA device, the PC also controls the basic current of the generator. First, the PC commands a pre-treatment cycle with a small electrical current that flows between each individual electrode and the ground plate. Thereby, the PC can obtain information about the length of each electrode. It is also possible to have the PC check which position in the grid is occupied by the electrode and which position is not occupied. The PC further executes the operational algorithm described in the following paragraphs.

  The PC further executes an operation algorithm. These treatment algorithms include a tumor and a safety margin that surrounds the tumor, even if the radio frequency electrodes are optimally performed and the tumor is large or the shape of the tumor is irregular Designed to obtain abundant and specific ablation zones. The parameters of the treatment algorithm can be preset or adapted manually.

The operating algorithm is based on the following pre-radio frequency input parameters:
The length of the non-insulated part of the electrode,
-Number of electrodes,
The distribution of the electrodes in the space, i.e. the pattern and the spacing between the electrodes,
-Tissue type, and-Whether tissue is perfused.

The operational algorithm may be further based on the following input parameters measured during radio frequency ablation:
The impedance between the electrode and the ground plate, or the impedance between the electrode and the reference electrode, or the impedance between the electrode pair.

The operational algorithm determines the following output parameters:
-Electrodes activated as a group,
The electrical mode in which each electrode group is activated, i.e. monopolar or bipolar,
-In bipolar mode, which electrode is activated as a positive electrode and which electrode is activated as a negative electrode,
The activation mode of the electrodes, i.e. sequential mode, simultaneous mode or switching mode,
-In the switching mode, the activation time interval of each electrode group and the order in which the groups are activated by cyclic movement;
Power output and current intensity, and duration of the entire cauterization procedure.

  An example algorithm was developed based on experimental studies using multiple electrodes in an extracorporeal bovine liver. There, the use of four parallel simple 3 cm electrodes, arranged in a square pattern that can have a bipolar current between two rows of two electrodes, with each row electrically connected in parallel, is very reliable and reproducible. Showed complete solidification of the area between the electrodes, 3-5 mm of solidification outside the area between the electrodes. Therefore, the electrode spacing is selected to be 2 cm or less, the power is selected to be 60 W or less, and the power is not using an algorithm with a predefined fixed duration, but rather is increased in impedance using automatic power cut-off. Until given. As a result, the duration of coagulation was 6-8 minutes.

  Experiments have shown that the bipolar mode between the two electrode groups is more efficient and reliable than the same four-electrode continuous monopolar activation or the same four-electrode continuous bipolar activation due to the Faraday effect.

  Furthermore, it was experimentally learned that the ideal power required to solidify the area between four similar electrodes having a non-insulating length Lcm is equal to 60 watts × L / 3.

  The experiment shows that the switching mode activates the first cube and more than the second cube to solidify two adjacent cubes of tissue determined by the two rows of electrodes in succession, the second of each row It was further shown that the electrode is more efficient than the continuous mode belonging to the first and second cubes. In fact, in continuous mode, the tissue in the vicinity of the electrode common to the compatible cuboid is completely dehydrated after the first cube solidifies. This hinders correct current flow in the second cube. Besides being more efficient, the switching mode also works faster than the continuous mode.

  Similarly, experiments have shown that the switching mode is more efficient than the simultaneous mode. In such a simultaneous mode, the current diminishes over a larger volume, which can cause problems in the case of large tumors. Furthermore, in the simultaneous mode, the current is pushed towards the boundary of the volume occupied by the electrode due to the Faraday effect. As a result, the necessary coagulation edge surrounding the desired treatment volume is enlarged. The resulting coagulation, in other words, is less reliable and predictable than the simultaneous mode.

  In a preferred embodiment of the invention, the electrodes are inserted into the tumor in a rectangular pattern with an electrode spacing of 2 cm parallel to each other. The entire tumor and a safety margin of 1 cm are covered. If the rectangular pattern electrode is outside the cover area, the electrode is placed near the outside in the area using the flexibility of the mesh or plate. The length of the electrode is adapted to the local thickness of the tumor, 1 cm above the front or upper boundary of the tumor and 1 cm below or below the tumor. Depending on the relative position to the tumor, three types of electrodes can be distinguished: a corner electrode that contacts healthy tissue in two directions, a side electrode that contacts healthy tissue in two directions, and no contact with healthy tissue Central electrode. The tissue is fully coagulated when the impedance between the central electrodes is increased 2-3 times. The square electrode is kept in a low impedance in order to maintain a state in contact with healthy tissue in two directions. In the side electrodes, an intermediate impedance rise is seen. In the case of uniform clotting, the impedance remains approximately constant throughout the treatment until the complete clotting point where a rapid increase in impedance is seen. As a general principle, the electrode block is activated after a certain manner in which all electrodes are activated for an equal amount of time. Several schemes that adhere to this general principle are described in the following paragraphs with reference to FIGS. 7, 8, 9, 10, 11, and 12, respectively.

  In the case of a 3 × 3 electrode and 2 × 2 electrode group, FIG. 7 shows that four normal activation patterns N1, N2, N3, and N4 are used once and the lower side electrode is lower than the central electrode. An activation pattern Z that compensates for activation is used twice, and an activation pattern H1 that compensates for activation of a lower corner electrode compared to the central electrode is used three times. A complete cycle consists of 9 sequential activations: H1-Z-H1-N2-Z-H1-N3-N4

  In the case of 4 × 3 electrodes, there is no solution using 2 × 2 electrode groups. FIG. 8 shows a solution with a 3 × 2 electrode group, where three normal activation patterns D1, D2 and D3 are used once and an activation pattern H2 is compensated once to compensate for the low activation of the corner electrodes. used. A complete cycle consists of four sequential activations: D1-D2-D3-H2

  FIG. 9 shows a similar activation scheme with 3 × 3 electrodes and 3 × 2 electrode groups. Two normal activation patterns D4 and D5 are followed by an activation pattern H3 that compensates for the low activation of the corner electrodes. In this case, the complete cycle consists of four sequential activations: D4-D5-H3, the 3 × 2 electrode group is advantageous compared to the 2 × 2 electrode group because the impedance is lower, This is because the current intensity is higher and the solidification is faster. In the case of 3 × 2 electrodes, a more powerful generator may be required.

  When three rows of positive electrodes and three rows of negative electrodes are used, the central portion between the rows and the electrodes is less solidified due to the Faraday effect. In the case of alternating rows, ie one row with positive-negative-positive electrodes and one row with negative-positive-negative electrodes, the central part between the electrodes is excessively coagulated as a result of centripetal current. Become. A solution to this problem is that the rows have electrodes of opposite polarity as shown in FIG. 10 and the rows have electrodes of alternating polarity as shown in FIG. It is to alternate with the centripetal method. This principle applies to both 3 × 3 electrode situations and 3 × 4 electrode situations.

  In the case of 4 × 4 electrodes, FIG. 12 shows an activation scheme with 4 × 2 electrode groups. The three normal activation patterns V1, V2, and V3 are followed by an activation pattern H4 that compensates for the low activation of the corner electrodes. A complete cycle consists of four sequential activations: V1-V2-V3-H4. After the centripetal cycle shown in FIG. 11, the centrifugation cycle is continued.

  In summary, the xy electrode can be activated in a row to obtain a uniform solidification. In this case, the row includes the larger x or y electrodes. In this way, the coagulation rate is increased and large distances between the corner electrodes that need to be activated separately are avoided. However, a more powerful generator is needed to enable activation of the electrode rows. For less powerful generators, other directions can be considered, with each row including the smaller x or y electrode. In the first half cycle, a row pattern is followed in which two adjacent groups of rows are activated one after the other. A centripetal polarity scheme is used. That is, each row contains either positive or negative electrodes. In order to compensate for the low activation of the corner electrodes, an additional activation of the group consisting of the first and last rows of electrodes is performed. In the second half cycle, the equivalent of centrifugation is received.

As soon as the impedance exceeds 25Ω, the generator is switched off. If longer electrodes are used and / or the electrode spacing is narrow and / or more electrodes are activated at the same time, the impedance is reduced and a more powerful generator is needed. The generator is also switched off immediately if the switch frequency is higher than 1/200 ms. The ideal switch interval is 200 milliseconds to 500 milliseconds. The ideal energy density is 4.2-5 watts / cm ³ to obtain uniform solidification within the area surrounded by the other electrodes without burning effects.

  FIG. 13 shows the uniqueness of the electrodes when the sphere or cylinder is to be solidified. Compared to a square or rectangle, the corner electrodes 1301, 1302, 1303, and 1304 move inward. The electrode is then activated as if it were still part of a square or rectangle. This scheme works in the case of a sphere with radius R, the central electrode has an active tip length 2R and the outer electrode has a length 2 / 3R. The electrode spacing is equal to R. This scheme is also useful for a cylindrical shape having a radius R and a height h. In this case, the electrode spacing is equal to R and the active tip length of all electrodes is equal to h. If adjacent electrodes have different active tip lengths, the shortest active tip length must be at least equal to 2/3 of the longest active tip length. Otherwise, the coagulation may be incomplete.

  As shown in FIG. 14, the cylindrical volume can also be solidified using a scheme 1401 with six electrodes instead of nine electrodes, ie, a scheme without a central electrode. The three electrodes have a positive polarity and the three electrodes have a negative polarity. The electrode sets having positive polarity are cycled and alternated as shown in FIG. 14 by the following schemes 1402, 1403 and 1404. The electrode spacing can be at most 2/3 of the active tip length h of the electrode.

  FIG. 15 gives an overview of the different elements in the preferred embodiment of the switch box forming part of the present invention. Each switch is connected to an electrode inserted into the tissue. All switches share a connection with the high and low output of the generator. The common controller in FIG. 15 applies a pseudo load. The controller measures the commonly applied generator voltage and connects to the reference electrode during impedance measurement. The host processor controls all the distributed controllers via an optically isolated communication bus. This is the only location where the actual concept of the matrix exists. The pseudo load is also controlled from this control location. To provide energy to the tissue, the host processor, for example, controls the switch so that adjacent electrodes are connected to the opposite polarity of the generator and current flows through the tissue. In order to measure the impedance of the tissue, the current is preferably measured between one electrode and a reference electrode or plate. When measured with respect to a common reference electrode, the measurement is independent of the impedance of neighboring electrodes. While applying energy to the tissue, the reference electrode is cut to avoid current leakage to this electrode. To perform impedance measurements, the same current as the treatment can be used, but only gives a fraction of the time required for tissue ablation. The amount of energy corresponding to the applied power multiplied by time is proportionally lower due to the shorter measurement time. Due to the general nature of the reference electrode, the current measurement can be performed with a common controller as well. This can simplify all other electrodes by eliminating the current measurement circuit from the electrodes. However, local measurements can also be used as a means of confirming correct operation during energy application to the tissue or as a means of interrupting the electrode in case of severe overcurrent. The same common controller connected to the reference electrode also performs the voltage measurements necessary to calculate the impedance of every node. The common controller also connects a pseudo load to the output of the generator when no other switch is activated.

  FIG. 16 shows a single switch connected to a common communication bus via an optical isolator. All switches consist of the same hardware and software, the only difference being the address value that allows to identify the message directed to each.

  The switch box can be constructed using electromechanical repeaters. Instead of mechanical repeaters with limited lifetime, MOSFETs can be considered. However, MOSFETs are not perfect isolators at the generator's relatively high output frequency. Even a low leakage MOSFET with a parasitic capacitor of about 40 pF between the drain and source will generate a significant amount of power between the high and low output of the generator. By constructing an AC switch using MOSFETs, two of these devices are placed in series, effectively increasing the overall impedance to 16 kΩ. These values are high compared to the on-state resistance which is about 0.1Ω. However, when a large amount of these devices are connected in parallel like a 5 × 5 matrix, the coupling impedance is reduced to 640Ω. This means that most of the output power of the generator is dissipated in the MOSFET and does not contribute to the cauterization process and a more powerful generator is required. In the current state of power MOSFETs, it is not practical to implement such a large switch matrix without wasting a lot of output power. Leakage can be eliminated using a small and highly durable repeater until a low leakage MOSFET is available.

  The matrix structure is virtual: all distributed processors share a common serial communication bus. Each processor is uniquely identified by a separate address on this bus. The concept of a matrix exists only in host processors that map addresses to a two-dimensional matrix via a lookup table.

  A local microcontroller is used to control the switch. The local microcontroller shares a common serial data bus line as well as a common reset error line. Communication is half duplex. Each slave node constantly monitors data lines driven by the master or host. When a command is addressed to the switch controller, the switch controller reacts only if it recognizes the address. Depending on the command, the controller activates or deactivates the output, or sends status and measurement information to the host. All serial interfaces share a common open drain line with a common pull-up resistor. Since the ground reference of each switch is floating, the communication interface must be optically isolated from the host processor and other nodes.

  An asynchronous serial interface is used to connect the processor to the common bus and the host processor. The communication speed is not very important because not all nodes need to be configured at the same time and not all nodes report measurement information at the same time. Only switches that are turned on and actively conducting current are required to perform current measurements and transmit these values over the communication bus. It is only during the identification phase that the entire matrix needs to be scanned.

  The generator requires a minimum load resistance. The common controller connects a 1 kΩ pseudo load resistor across the generator output during times when the other switches are not active so that the generator is not in self-protection mode. This combination of the pseudo load and the common voltage measurement allows for the complete reuse of the electrical switch circuit board for this purpose. The control of the pseudo load must be handled by the host processor because it is the only point where the state of each electrode is known.

  The PC can log different parameters before and throughout the treatment: current, power, measured impedance value, position occupied by the electrodes, active part length of these electrodes, etc. These parameters can be stored and visualized in a graph. It can also be printed and stored in the patient's medical record.

  During RFA treatment, electrode position, electrode impedance, active portion length, and activation state may be visualized in a two-dimensional (2D) or three-dimensional (3D) representation on a screen, eg, a PC screen.

  As shown in FIG. 17, the PC screen 1700 can visualize the position of the electrode represented by the dot 1701 and the area controlled by each electrode represented by the square 1702 in a 2D manner. The square color may represent the measured impedance. The color scale is varied from 0Ω to, for example, up to 3 times the pre-treatment impedance, or alternatively to a fixed value of, for example, 300Ω to maximize the visibility of impedance changes during the ablation process. This is indicated by the color scale 1703 on the screen 1700. A square representing an electrode position not occupied by the electrode is black. For each square, a numerical value indicating the measured impedance may or may not be shown on the screen, or the value may be displayed by clicking the square mouse. The square color can be color coded, for example red, green or black. As an example, black means that the electrode is not activated, green means that the electrode functions as a positive electrode in bipolar electric mode, and red means that the electrode functions as a negative electrode in bipolar electric mode It means to do. In this way, the correct activation of the electrode group can be visually monitored.

  As further shown in FIG. 18, the PC screen 1800 can add a third dimension based on the length of the non-insulated portion of each electrode. The square is then replaced with, for example, bars 1801, 1802, 1803, and the bars follow the axis of each electrode. Screen 1800 further shows a color scale 1806 ranging from 0Ω to 300Ω.

  The resulting 2D or 3D visual image can be fused to 2D or 3D imaging of the tumor 1805 so that the position of the electrodes and the progress of the ablation process can be visually monitored. This is shown in FIG.

  The PC further allows patient data such as name, date of birth, and other patient related information to be easily introduced for recording. The PC provides an easy-to-use menu that allows different functions to be selected.

  The generator in the RFA apparatus according to the present invention can be commercially available or dedicated. Preferably, the generator should be able to output up to 500 watts and be able to work with low impedance.

  When using simple electrodes 1901, 1902, 1903, and 1904 used in bipolar or multipolar mode, a tissue edge 1905 from 0 cm to 1 cm solidifies outside the volume enclosed by the outer electrodes. This is due to the current applied to the electrode from the outside, as shown in FIG. In order to avoid this undesirable coagulation 1905 outside the volume enclosed by the outer electrode, the outer electrode can be partially shielded with an insulating sheet or coating, eg, a plastic sheet 2002, typically over 180 degrees. Such a partially shielded electrode 2001 is shown in FIG. As a result, there is no undesirable solidification outside the remaining electrode cage, or a substantially narrower edge. This is shown in FIG. 21, which shows the coagulation zone 2105 when four partially shielded square electrodes 2101, 2102, 2103, and 2104 are used.

  Although the invention has been described with reference to particular embodiments, the invention is not limited to the details of the exemplary embodiments described above, and the invention can be embodied with various changes and modifications without departing from the scope of the invention. Those skilled in the art will appreciate that this is possible. The embodiments are, therefore, to be considered in all respects only as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, and thus the equivalents of the claims All modifications that come within the meaning and range of are intended to be included within the scope of the claims. In other words, it is within the basic fundamental principles and is intended to encompass any and all modifications, variations, or equivalents whose essential attributes are claimed in this patent application. Further, the term “comprising” or “including” does not exclude other elements or steps, and the term “a” or “an” does not exclude a plurality, such as a computer system, processor, or another integrated unit, etc. It will be appreciated by the reader of this patent application that a single element may fulfill the functions of several means recited in the claims. Any reference signs in the claims should not be construed as limiting the claim concerned. Terms such as “first”, “second”, third ”,“ a ”,“ b ”,“ c ”, and the like are used in the description or in the claims to refer to similar elements or Introduced to distinguish steps, does not necessarily describe order or temporal order. Similarly, terms such as “upper”, “lower”, “upper”, “lower” and the like have been introduced for purposes of illustration and do not necessarily indicate relative positions. The terms so used are interchangeable under appropriate circumstances, and embodiments of the present invention can operate in accordance with the present invention in a different order or orientation than those described or shown above. I want you to understand.

Claims (22)

A mesh or plate (100) with holes (101) in a grid holding the electrodes (501, ..., 510);
A plurality of electrodes (501,..., 510) having active tip lengths that can be adapted;
-Means for visualizing and investigating the insertion depth of each of said electrodes (501, ..., 510) in diseased tissue (500);
-Connectable to the plurality of electrodes (501, ..., 510) and distribute current between the plurality of electrodes (501, ..., 510) during a radio frequency ablation (RFA) process. A switch box to be adapted,
A control unit for controlling the switch box;
Means (1700, 1800) for monitoring the radio frequency ablation (RFA) process;
A radiofrequency ablation (RFA) device of the diseased tissue (500) comprising:
A plurality of the holes (101) of the grid are occupied by electrodes (501, ..., 510) arranged in rows;
The control unit is
-Electrode group,
The electrical mode for activating each electrode group and the polarity of the electrodes in each electrode, wherein the control unit has a centrifuge mode with electrodes of the same polarity in the row and a polarity with alternating polarity of the rows. Electrical mode and electrode polarity, adapted to activate the electrodes during successive cycles alternating with the heart mode,
A group activation mode, which activates sequentially, simultaneously and by switching ,
-Time intervals and sequence of activation of said group;
-Power output and current intensity supplied to each electrode ,
-Adapted to determine the duration of the radio frequency ablation (RFA) process, whereby each electrode is activated for an amount of time such that approximately equal radio frequency power is applied to diseased tissue per unit volume A device, characterized in that The apparatus of claim 1.
The holes (101, 111) in the grid form the following shapes:
A rectangular pattern,
An apparatus comprising one or more of spherical patterns; The apparatus of claim 1.
The mesh or plate (209) includes a plug (202, 203) for connecting to the electrode (201) inserted into the hole for each hole, and the plug (202, 203) is positioned around the hole. The apparatus characterized by being made. The apparatus of claim 1.
The mesh or plate (229) includes a plug (222, 223) for connecting to the electrode (221) inserted into the hole (227) for each hole (227), and the plug (222, 223) Device positioned in the vicinity of the hole (227). The apparatus according to claim 3 or 4,
The mesh or plate (300) is
An electrical cable connector (304) for connection to the switch box;
Electrical wiring (302, 303) between each of the plugs (301) and the electrical cable connector (304);
A device comprising: The apparatus of claim 1.
The mesh, plate, or intermediate sterilization plate (404)
A visual indicator for each hole, said visual indicator being adapted to illuminate when an electrode (405) is inserted into said hole, said visual indicator being connected to said electrode (405) Operatively coupled to a visual indicator on the switch box indicating a plug on the box, the visual indicator on the mesh or plate, and the visual indicator on the switch box, the electrode to the switch box (405) An apparatus which enables connection without error. The apparatus of claim 6.
The device characterized in that the visual indicator on the mesh, plate or intermediate sterilization plate (404) consists of a color LED. The apparatus of claim 1.
The mesh or plate constitutes a plate (404);
The apparatus further comprising a robot arm (403) for positioning the plate (40 4 ). The apparatus of claim 1.
The apparatus further comprising a robot arm (412) for positioning the plurality of electrodes (413) substantially horizontally with respect to each other.   The apparatus of claim 1, wherein each electrode (600) of the plurality of electrodes has an electrically insulating slide sheet (602) that conforms to the active tip length (601).   The device according to claim 10, characterized in that the electrically insulating sheet (602) is coated with a coating that is visible through ultrasound. The apparatus of claim 1.
One or more of the plurality of electrodes (2001) is partially shielded along the outer periphery, thereby directing the generated RF field near the border of the diseased tissue . The apparatus of claim 12, wherein
Each of a plurality of shielding electrodes (2101, 1022, 2103, 2104) has a shape that prevents rotation of the partially shielded electrode when the partially shielded electrode is inserted into the diseased tissue. A device comprising:   The apparatus of claim 1, wherein the plurality of electrodes have different lengths. The apparatus of claim 1.
The means for monitoring is
-A ground plate;
-Means for measuring impedance between the ground plate and each electrode of the plurality of electrodes;
A device comprising: The apparatus of claim 1.
The means for monitoring is
-An apparatus comprising means for measuring the impedance between each pair of said plurality of electrodes. The apparatus of claim 1.
The means for monitoring is
An apparatus comprising means for measuring impedance between a reference electrode and each non-reference electrode of the plurality of electrodes. An apparatus according to claim 15, 16 or 17,
The apparatus is as follows:
Means for converting the impedance into information indicative of the occupied position in the mesh or plate;
One or more of: means for converting the impedance into information indicative of the active tip length of each electrode; and- means for converting the impedance into information indicative of the progress of the radio frequency ablation (RFA) process. An apparatus further comprising: The apparatus of claim 1.
An apparatus further comprising means for logging parameters prior to and during the radio frequency ablation (RFA) process. The apparatus of claim 1.
The apparatus further comprising means (1700) for visualizing the progress of the radio frequency ablation (RFA) process via a color in response to a two-dimensional (2D) representation and impedance measurement. The apparatus of claim 1.
The apparatus further comprises means (1800) for visualizing the progress of the radio frequency ablation (RFA) process via a three-dimensional (3D) representation taking into account the active tip length of the electrode and the color responsive to impedance measurement. Equipment. The apparatus of claim 1.
The apparatus further comprising an RF control interface of the switch box and / or power unit.

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